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The Case for Network Coding for Collective Communication on HPC Interconnection Networks
Ahmed SHALABY Ikki FUJIWARA Michihiro KOIBUCHI
IEICE TRANSACTIONS on Information and Systems
Publication Date: 2015/03/01
Online ISSN: 1745-1361
Type of Manuscript: PAPER
Category: Information Network
interconnection networks, collective communication, network coding, high-performance computing,
Full Text: FreePDF
Recently network bandwidth becomes a performance concern particularly for collective communication since bisection bandwidths of supercomputers become far less than their full bisection bandwidths. In this context we propose the use of a network coding technique to reduce the number of unicasts and the size of data transferred in latency-sensitive collective communications in supercomputers. Our proposed network coding scheme has a hierarchical multicasting structure with intra-group and inter-group unicasts. Quantitative analysis show that the aggregate path hop counts by our hierarchical network coding decrease as much as 94% when compared to conventional unicast-based multicasts. We validate these results by cycle-accurate network simulations. In 1,024-switch networks, the network reduces the execution time of collective communications as much as 70%. We also show that our hierarchical network coding is beneficial for any packet size.